The present invention relates to innovative curves and series of curves for conveyors, of the type having magnets fitted therein for keeping a conveyor chain in place. Curves for chain transporting installations are known which are provided with pockets or cavities in which magnets identical with each other are fitted and to which said magnets are differently fastened along the whole extension of a guide. For example, curves have been proposed in which a plurality of cavities, spaced apart the same distance along the guide extension, are formed in the guide body and in each cavity an identical magnet is housed. Curves of this type are shown in European Patents EP 0 159 074 and EP 0 509 605, for example.
It has been found however that by adopting known solutions the conveyor travelling over a curve is subjected to wobbling, jerks and in general to variations in the pulling force that do not appear to be directly due to the mechanical features of the sliding surfaces alone.
In accordance with the present invention, this is to be ascribed to irregularities in the magnetic field caused by an inappropriate distribution of the magnets as proposed in known chains. It is also to take into consideration the fact that, in order to optimise production, full series of curves having different extensions, radii of curvature, etc. employ the same magnet size.
The general object of the present invention is to obviate the above mentioned drawbacks by providing magnetic curves having improved sliding features enabling a more satisfactory distribution of the magnetic field. It is a further object of the invention to obtain a satisfactory distribution of the field in curves of different extension and geometry with use of a limited number of different typologies of magnets, so as to standardise construction of curve series.